Exposure apparatus, exposure method, and method for producing device

ABSTRACT

A liquid immersion exposure apparatus includes an optical member through which an exposure beam passes, a flow passage in which a liquid flows, the flow passage being in fluidic communication with a space between the optical member and an object opposite to the optical member, and an opening at which a plurality of slits are provided, and from which the liquid is supplied to the space through the flow passage.

CROSS-REFERENCE

This is a Divisional of application Ser. No. 11/147,373 filed Jun. 8,2005, which is a Continuation of International Application No.PCT/JP03/015735 filed on Dec. 9, 2003 and that claims the conventionalpriority of Japanese patent Application No. 2002-357931 filed on Dec.10, 2002. The disclosures of these applications are incorporated hereinby reference in their entireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an exposure apparatus and an exposuremethod for performing the exposure with an image of a pattern projectedby a projection optical system in a state in which at least a part of aspace between the projection optical system and a substrate is filledwith a liquid. The present invention also relates to a method forproducing a device.

2. Description of the Related Art

Semiconductor devices and liquid crystal display devices are produced bythe so-called photolithography technique in which a pattern formed on amask is transferred onto a photosensitive substrate. The exposureapparatus, which is used in the photolithography step, includes a maskstage for supporting the mask and a substrate stage for supporting thesubstrate. The pattern on the mask is transferred onto the substrate viaa projection optical system while successively moving the mask stage andthe substrate stage. In recent years, it is demanded to realize thehigher resolution of the projection optical system in order to respondto the further advance of the higher integration of the device pattern.As the exposure wavelength to be used is shorter, the resolution of theprojection optical system becomes higher. As the numerical aperture ofthe projection optical system is larger, the resolution of theprojection optical system becomes higher. Therefore, the exposurewavelength, which is used for the exposure apparatus, is shortened yearby year, and the numerical aperture of the projection optical system isincreased as well. The exposure wavelength, which is dominantly used atpresent, is 248 nm of the KrF excimer laser. However, the exposurewavelength of 193 nm of the ArF excimer laser, which is shorter than theabove, is also practically used in some situations. When the exposure isperformed, the depth of focus (DOF) is also important in the same manneras the resolution. The resolution R and the depth of focus δ arerepresented by the following expressions respectively.

R=k ₁•λ/NA  (1)

δ=±k ₂•λ/NA²  (2)

In the expressions, λ represents the exposure wavelength, NA representsthe numerical aperture of the projection optical system, and k₁ and k₂represent the process coefficients. According to the expressions (1) and(2), the following fact is appreciated. That is, when the exposurewavelength λ is shortened and the numerical aperture NA is increased inorder to enhance the resolution R, then the depth of focus δ isnarrowed.

If the depth of focus δ is too narrowed, it is difficult to match thesubstrate surface with respect to the image plane of the projectionoptical system. It is feared that the margin is insufficient during theexposure operation. Accordingly, the liquid immersion method has beensuggested, which is disclosed, for example, in International PublicationNo. 99/49504 as a method for substantially shortening the exposurewavelength and widening the depth of focus. In this liquid immersionmethod, the space between the lower surface of the projection opticalsystem and the substrate surface is filled with a liquid such as wateror any organic solvent to utilize the fact that the wavelength of theexposure light beam in the liquid is 1/n as compared with that in theair (n represents the refractive index of the liquid, which is about 1.2to 1.6 in ordinary cases) so that the resolution is improved and thedepth of focus is magnified about n times.

When the exposure is performed while making the liquid to flow throughthe space between the projection optical system and the substrate, orwhen the exposure is performed while moving the substrate with respectto the projection optical system in a state in which the space betweenthe projection optical system and the substrate is filled with theliquid, then there is such a possibility that the liquid may beexfoliated from the projection optical system and/or the substrate. Aninconvenience arises such that the pattern image, which is to betransferred to the substrate, is deteriorated. In other cases, thepattern image is deteriorated as well when any turbulence appears in theliquid flow when the exposure is performed while making the liquid toflow through the space between the projection optical system and thesubstrate.

SUMMARY OF THE INVENTION

The present invention has been made taking the foregoing circumstancesinto consideration, an object of which is to provide an exposureapparatus, an exposure method, and a method for producing a device, inwhich a pattern can be transferred accurately by arranging a liquid in adesired state when an exposure process is performed while filling aspace between a projection optical system and a substrate with theliquid. It is noted that parenthesized numerals or symbols affixed torespective elements merely exemplify the elements by way of example,with which it is not intended to limit the respective elements.

In order to achieve the object as described above, the present inventionadopts the following constructions.

According to a first aspect of the present invention, there is providedan exposure apparatus which exposes a substrate by transferring an imageof a pattern through a liquid onto the substrate, the exposure apparatuscomprising:

a projection optical system which projects the image of the pattern ontothe substrate, wherein:

a portion of the projection optical system, which makes contact with theliquid, is surface-treated to adjust affinity for the liquid.

In the exposure apparatus of the present invention, the surfacetreatment is applied to the portion of the projection optical system(hereinafter appropriately referred to as “liquid contact portion”)which makes contact with the liquid in order to adjust the affinity forthe liquid. Therefore, the liquid is maintained in a desired statebetween the projection optical system and the substrate. For example, ifthe affinity of the liquid contact portion for the liquid is too low,any phenomenon, in which any harmful influence is exerted on the liquidimmersion exposure, arises, for example, such that the liquid isexfoliated from the contact portion, and/or any bubble is generated. Onthe other hand, if the affinity of the liquid contact portion for theliquid is too high, any inconvenience arises in some cases, for example,such that the liquid is spread while causing excessive wetting withrespect to the contact portion and the liquid outflows from the spacebetween the projection optical system and the substrate. On thecontrary, in the case of the exposure apparatus of the presentinvention, the affinity is adjusted with respect to the liquid disposedat the liquid contact portion of the projection optical system.Therefore, the liquid immersion state is reliably maintained between thesubstrate and the projection optical system even in the case of the fullfield exposure in which the substrate stands still with respect to theexposure light beam during the exposure as well as in the case of thescanning type exposure apparatus in which the substrate is moved by amovable stage during the exposure.

According to a second aspect of the present invention, there is providedan exposure apparatus which exposes a substrate by transferring an imageof a pattern through a liquid onto the substrate, the exposure apparatuscomprising:

a projection optical system which projects the image of the pattern ontothe substrate, wherein:

the projection optical system has a first surface area which includes asurface of an optical element disposed at a tip of the projectionoptical system, and a second surface area which is disposed around thefirst surface area; and

affinity of the first surface area for the liquid is higher thanaffinity of the second surface area for the liquid.

According to the present invention, the affinity for the liquid of thefirst surface area including the optical element disposed at the tip ofthe projection optical system is made higher than that of the secondsurface area disposed therearound. Accordingly, the liquid is stablyarranged on the optical path for the exposure light beam owing to thefirst surface area. Further, the liquid is not spread with the wettingto the surroundings owing to the second surface area, and thus does notoutflow to the outside. Therefore, the liquid can be stably arranged onthe optical path for the exposure light beam even in the case of thefull field exposure in which the substrate stands still with respect tothe exposure light beam during the exposure as well as in the case ofthe scanning type exposure in which the substrate is moved with respectto the exposure light beam during the exposure.

According to a third aspect of the present invention, there is providedan exposure apparatus which exposes a substrate by illuminating apattern with an exposure beam and transferring an image of the patternthrough a liquid onto the substrate, the exposure apparatus comprising:

a projection optical system which projects the image of the pattern ontothe substrate; and

a liquid immersion unit which fills, with the liquid, at least a part ofa space between the projection optical system and the substrate,wherein:

a conditional expression (v•d•ρ)/μ≦2,000 is satisfied provided that drepresents a thickness of the liquid, v represents a velocity of a flowof the liquid between the projection optical system and the substrate, ρrepresents a density of the liquid, and μ represents a coefficient ofviscosity of the liquid.

According to the present invention, the condition, under which theliquid is maintained in at least the part of the space between theprojection optical system and the substrate, is set so that theconditional expression described above is satisfied. Accordingly, noturbulence arises in the liquid. Therefore, it is possible to suppressany inconvenience which would be otherwise caused, for example, suchthat the pattern image to be projected onto the substrate isdeteriorated due to the turbulence of the liquid.

According to a fourth aspect of the present invention, there is providedan exposure apparatus which exposes a substrate by illuminating apattern of a mask with an exposure beam and transferring an image of thepattern through a liquid onto the substrate, the exposure apparatuscomprising:

a projection optical system which projects the image of the pattern ontothe substrate; and

a liquid immersion unit which fills, with the liquid, at least a part ofa space between the projection optical system and the substrate,wherein:

the liquid flows as a laminar flow in parallel to a scanning directionof the substrate.

According to the present invention, the liquid immersion state iscontrolled by various methods, and thus the liquid flows while formingthe laminar flow in parallel to the scanning direction of the substrateduring the exposure. Therefore, it is possible to avoid thedeterioration of the pattern image to be projected onto the substrate.Further, no unnecessary vibration is generated, for example, in theprojection optical system which makes contact with the liquid as well asin the wafer and the substrate stage which holds the wafer. The flow ofthe liquid can be made into the laminar flow, for example, bycontrolling the amount of supply (recovery) of the liquid by the liquidimmersion unit, adjusting the structure of the liquid supply nozzle ofthe liquid immersion unit, and/or adjusting the velocity when thesubstrate is moved during the exposure.

According to a fifth aspect of the present invention, there is providedan exposure apparatus which exposes a substrate by illuminating apattern with an exposure beam and transferring an image of the patternthrough a liquid onto the substrate, the exposure apparatus comprising:

a projection optical system which projects the image of the pattern ontothe substrate;

a liquid immersion unit which supplies the liquid onto only thesubstrate; and

a control unit which controls the liquid immersion unit, wherein:

the control unit controls the liquid immersion unit so that the supplyof the liquid is stopped during the exposure of the substrate.

According to the present invention, the liquid immersion unit iscontrolled such that the liquid is not supplied during the exposure forthe substrate. Accordingly, the photosensitive material, which has beenapplied onto the substrate, is not damaged. It is possible to avoid thedeterioration of the pattern to be formed on the substrate. Further, thepositional relationship between the projection optical system and thesubstrate can be stably maintained in a desired state.

According to a sixth aspect of the present invention, there is providedan exposure method for exposing a substrate by projecting an image of apattern onto the substrate by using a projection optical system, theexposure method comprising:

applying a surface treatment to a surface of the substrate before theexposure in order to adjust affinity for the liquid;

filling at least a part of a space between the projection optical systemand the substrate with the liquid; and

projecting the image of the pattern onto the substrate through theliquid.

According to the present invention, the surface treatment is applied tothe surface of the substrate depending on the affinity for the liquidbefore performing the liquid immersion exposure. Accordingly, the liquidcan be maintained on the substrate in a state preferable for the liquidimmersion exposure. For example, if the affinity for the liquid is toolow, any inconvenience arises, for example, such that the liquid isexfoliated from the surface of the substrate, and/or any bubble isgenerated. On the other hand, if the affinity for the liquid is toohigh, any inconvenience arises in some cases, for example, such that theliquid is spread excessively while causing wetting on the substrate. Onthe contrary, when the appropriate surface treatment is applied to thesubstrate surface in consideration of the affinity for the liquid as inthe exposure method of the present invention, then the liquid can bemaintained in a desired state on the substrate, and it is possible toappropriately perform the recovery and the removal of the liquid on thesubstrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic arrangement illustrating an embodiment of theexposure apparatus of the present invention.

FIG. 2 shows an exemplary arrangement of supply nozzles and recoverynozzles.

FIG. 3 shows an exemplary arrangement of supply nozzles and recoverynozzles.

FIG. 4 schematically illustrates areas in which a projection opticalsystem and a substrate are surface-treated.

FIGS. 5A to 5C schematically illustrates situations in which the liquidflows between a substrate and a projection optical system which are notsurface-treated.

FIGS. 6A to 6C schematically illustrates situations in which the liquidflows between a substrate and a projection optical system which aresurface-treated.

FIG. 7 illustrates another embodiment of the present invention.

FIGS. 8A and 8B show other embodiments of supply nozzles.

FIG. 9 shows a cover glass provided over a substrate.

FIG. 10 shows a flow chart illustrating exemplary steps for producing asemiconductor device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

An explanation will be made below about the exposure apparatus and themethod for producing the device according to the present invention withreference to the drawings. However, the present invention is not limitedthereto. FIG. 1 shows a schematic arrangement illustrating an embodimentof the exposure apparatus of the present invention.

With reference to FIG. 1, an exposure apparatus EX includes a mask stageMST which supports a mask M, a substrate stage PST which supports asubstrate P, an illumination optical system IL which illuminates, withan exposure light beam EL, the mask M supported by the mask stage MST, aprojection optical system PL which performs projection exposure for thesubstrate P supported by the substrate stage PST with an image of apattern of the mask M illuminated with the exposure light beam EL, and acontrol unit CONT which collectively controls the overall operation ofthe exposure apparatus EX.

The embodiment of the present invention will now be explained asexemplified by a case of the use of the scanning type exposure apparatus(so-called scanning stepper) as the exposure apparatus EX in which thesubstrate P is exposed with the pattern formed on the mask M whilesynchronously moving the mask M and the substrate P in mutuallydifferent directions (opposite directions) in the scanning directions.In the following explanation, the Z axis direction is the directionwhich is coincident with the optical axis AX of the projection opticalsystem PL, the X axis direction is the synchronous movement direction(scanning direction) for the mask M and the substrate P in the planeperpendicular to the Z axis direction, and the Y axis direction is thedirection (non-scanning direction) perpendicular to the Z axis directionand the Y axis direction. The directions about the X axis, the Y axis,and the Z axis are designated as θX, θY, and θZ directions respectively.The term “substrate” referred to herein includes those obtained byapplying a resist on a semiconductor wafer, and the term “mask” includesa reticle formed with a device pattern to be subjected to the reductionprojection onto the substrate.

The illumination optical system IL is used so that the mask M, which issupported on the mask stage MST, is illuminated with the exposure lightbeam EL. The illumination optical system IL includes, for example, anexposure light source, an optical integrator which uniformizes theilluminance of the light flux radiated from the exposure light source, acondenser lens which collects the exposure light beam EL supplied fromthe optical integrator, a relay lens system, and a variable fielddiaphragm which sets the illumination area on the mask M illuminatedwith the exposure light beam EL to be slit-shaped. The predeterminedillumination area on the mask M is illuminated with the exposure lightbeam EL having a uniform illuminance distribution by the illuminationoptical system IL. Those usable as the exposure light beam EL radiatedfrom the illumination optical system IL include, for example, emissionlines (g-ray, h-ray, i-ray) in the ultraviolet region radiated, forexample, from a mercury lamp, far ultraviolet light beams (DUV lightbeams) such as the KrF excimer laser beam (wavelength: 248 nm), andvacuum ultraviolet light beams (VUV light beams) such as the ArF excimerlaser beam (wavelength: 193 nm) and the F₂ laser beam (wavelength: 157nm). In this embodiment, the ArF excimer laser beam is used.

The mask stage MST supports the mask M. The mask stage MST istwo-dimensionally movable in the plane perpendicular to the optical axisAX of the projection optical system PL, i.e., in the XY plane, and it isfinely rotatable in the OZ direction. The mask stage MST is driven by amask stage-driving unit MSTD such as a linear motor. The maskstage-driving unit MSTD is controlled by the control unit CONT. Theposition in the two-dimensional direction and the angle of rotation ofthe mask M on the mask stage MST are measured in real-time by a laserinterferometer. The result of the measurement is outputted to thecontrol unit CONT. The control unit CONT drives the mask stage-drivingunit MSTD on the basis of the result of the measurement obtained by thelaser interferometer to thereby position the mask M supported on themask stage MST.

The projection optical system PL projects the pattern on the mask M ontothe substrate P at a predetermined projection magnification β to performthe exposure. The projection optical system PL includes a plurality ofoptical elements (lenses). The optical elements are supported by abarrel PK formed of a metal member, for example, stainless steel (SUS403). In this embodiment, the projection optical system PL is areduction system having the projection magnification β which is, forexample, 1/4 or 1/5. The projection optical system PL may be any one ofthe 1× magnification system and the magnifying system. The planeparallel plate (optical element) 60, which is formed of a glass membersuch as quartz and calcium fluoride (fluorite), is provided at the tipsection 7 on the side of the substrate P of the projection opticalsystem PL of this embodiment. The optical element 60 is provideddetachably (exchangeably) with respect to the barrel PK. The tip section7 of the projection optical system PL includes the optical element 60and a part of the barrel (holding member) PK for holding the same.

The substrate stage PST supports the substrate P. The substrate stagePST includes a Z stage 51 which holds the substrate P by the aid of asubstrate holder, an XY stage 52 which supports the Z stage 51, and abase 53 which supports the XY stage 52. The substrate stage PST isdriven by a substrate stage-driving unit PSTD such as a linear motor.The substrate stage-driving unit PSTD is controlled by the control unitCONT. When the Z stage 51 is driven, the substrate P, which is held onthe Z stage 51, is subjected to the control of the position (focusposition) in the Z axis direction and the positions in the θX and θYdirections. When the XY stage 52 is driven, the substrate P is subjectedto the control of the position in the XY directions (position in thedirections substantially parallel to the image plane of the projectionoptical system PL). That is, the Z stage 51 controls the focus positionand the angle of inclination of the substrate P so that the surface ofthe substrate P is adjusted to match the image plane of the projectionoptical system PL in the auto-focus manner and the auto-leveling manner.The XY stage 52 positions the substrate P in the X axis direction andthe Y axis direction. It goes without saying that the Z stage and the XYstage may be provided as an integrated body.

A movement mirror 54, which is movable together with the substrate stagePST with respect to the projection optical system PL, is provided on thesubstrate stage PST (Z stage 51). A laser interferometer 55 is providedat a position opposed to the movement mirror 54. The angle of rotationand the position in the two-dimensional direction of the substrate P onthe substrate stage PST are measured in real-time by the laserinterferometer 55. The result of the measurement is outputted to thecontrol unit CONT. The control unit CONT drives the substratestage-driving unit PSTD on the basis of the result of the measurement ofthe laser interferometer 55 to thereby position the substrate Psupported on the substrate stage PST.

In this embodiment, the liquid immersion method is applied in order thatthe resolution is improved by substantially shortening the exposurewavelength and the depth of focus is substantially widened. Therefore,the space between the surface of the substrate P and the tip section 7of the projection optical system PL is filled with the predeterminedliquid 50 at least during the period in which the image of the patternon the mask M is transferred onto the substrate P. As described above,the optical element 60 and the part of the barrel PK are arranged at thetip section 7 of the projection optical system PL. The liquid 50 makescontact with the optical element (glass member) 60 and the barrel (metalmember) PK. In this embodiment, pure water is used for the liquid 50.The exposure light beam EL, which is not limited to only the ArF excimerlaser beam, can be transmitted through pure water, even when theexposure light beam EL is, for example, the emission line (g-ray, h-ray,i-ray) in the ultraviolet region radiated, for example, from a mercurylamp or the far ultraviolet light beam (DUV light beam) such as the KrFexcimer laser beam (wavelength: 248 nm).

The exposure apparatus EX includes a liquid supply unit (liquidimmersion unit, supply unit) 1 which supplies the predetermined liquid50 to a space 56 between the substrate P and the tip section 7 of theprojection optical system PL, and a liquid recovery unit (liquidimmersion unit, recovery unit) 2 which recovers the liquid 50 from thespace 56. The liquid supply unit 1 is provided to allow the liquid 50 toflow in parallel to the scanning direction of the substrate P to atleast a part of the space between the projection optical system PL andthe substrate P. The liquid supply unit 1 includes, for example, a tankfor accommodating the liquid 50, and a pressurizing pump. One end of asupply tube 3 is connected to the liquid supply unit 1. Supply nozzles 4are connected to the other end of the supply tube 3. The liquid supplyunit 1 supplies the liquid 50 to the space 56 through the supply tube 3and the supply nozzles 4.

The liquid recovery unit 2 includes, for example, a suction pump, and atank for accommodating the recovered liquid 50. One end of a recoverytube 6 is connected to the liquid recovery unit 2. Recovery nozzles 5are connected to the other end of the recovery tube 6. The liquidrecovery unit 2 recovers the liquid 50 from the space 56 through therecovery nozzles 5 and the recovery tube 6. When the space 56 is filledwith the liquid 50, then the control unit CONT drives the liquid supplyunit 1 so that the liquid 50, which is in a predetermined amount perunit time, is supplied to the space 56 through the supply tube 3 and thesupply nozzles 4, and the control unit CONT drives the liquid recoveryunit 2 so that the liquid 50, which is in a predetermined amount perunit time, is recovered from the space 56 through the recovery nozzles 5and the recovery tube 6. Accordingly, the liquid 50 is retained in thespace 56 between the substrate P and the tip section 7 of the projectionoptical system PL.

During the scanning exposure, a pattern image of a part of the mask M isprojected onto the rectangular projection area disposed just under anend surface 60A. The mask M is moved at the velocity V in the −Xdirection (or in the +X direction) with respect to the projectionoptical system PL, in synchronization with which the substrate P ismoved at the velocity β•V (β is the projection magnification) in the +Xdirection (or in the −X direction) by the aid of the XY stage 52. Afterthe completion of the exposure for one shot area, the next shot area ismoved to the scanning start position in accordance with the stepping ofthe substrate P. The exposure process is successively performedthereafter for each of the shot areas in the step-and-scan manner. Thisembodiment is designed so that the liquid 50 is allowed to flow in thesame direction as the movement direction of the substrate in parallel tothe movement direction of the substrate P.

FIG. 2 shows the positional relationship among the tip section 7 of theprojection optical system PL, the supply nozzles 4 (4A to 4C) forsupplying the liquid 50 in the X axis direction, and the recoverynozzles 5 (5(a), 5(b)) for recovering the liquid 50. In FIG. 2, the tipsection 7 (end surface 60A of the optical element 60) has a rectangularshape which is long in the Y axis direction. The three supply nozzles 4Ato 4C are arranged on the side in the +X direction, and the two recoverynozzles 5(a), 5(b) are arranged on the side in the −X direction so thatthe tip section 7 of the projection optical system PL is interposedthereby in the X axis direction. The supply nozzles 4A to 4C areconnected to the liquid supply unit 1 through the supply tube 3, and therecovery nozzles 5(a), 5(b) are connected to the liquid recovery unit 2through the recovery tube 4. Further, the supply nozzles 8(a) to 8C andthe recovery nozzles 9A, 9B are arranged at positions obtained byrotating, by substantially 180°, the positions of the supply nozzles 4Ato 4C and the recovery nozzles 5(a), 5(b) about the center of the tipsection 7. The supply nozzles 4A to 4C and the recovery nozzles 9A, 9Bare alternately arranged in the Y axis direction. The supply nozzles8(a) to 8C and the recovery nozzles 5(a), 5(b) are alternately arrangedin the Y axis direction. The supply nozzles 8(a) to 8C are connected tothe liquid supply unit 1 through the supply tube 10. The recoverynozzles 9A, 9B are connected to the liquid recovery unit 2 through therecovery tube 11. The liquid is supplied from the nozzles so that no gasportion is formed between the projection optical system PL and thesubstrate P.

As shown in FIG. 3, the supply nozzles 31, 32 and the recovery nozzles33, 34 may be also provided on the both sides in the Y direction withthe tip section 7 intervening therebetween. The supply nozzles and therecovery nozzles can be used to stably supply the liquid 50 to the spacebetween the projection optical system PL and the substrate P even duringthe movement of the substrate P in the non-scanning direction (Y axisdirection) when the stepping movement is performed.

The shape of the nozzle is not specifically limited. For example, twopairs of the nozzles may be used to supply or recover the liquid 50 forthe long side of the tip section 7. In this arrangement, the supplynozzles and the recovery nozzles may be arranged while being alignedvertically in order that the liquid 50 can be supplied and recovered inany one of the directions of the +X direction and the −X direction.

FIG. 4 shows a magnified view illustrating those disposed in thevicinity of the tip section 7 of the projection optical system PL. Asshown in FIG. 4, the surface treatment, which depends on the affinityfor the liquid 50, is applied to the tip section 7 of the projectionoptical system PL. The tip section 7 is a portion to make contact withthe liquid 50 when the substrate P is moved in the scanning direction (Xaxis direction) in order to perform the scanning exposure. The tipsection 7 includes a lower surface 7A of the projection optical systemPL which includes the lower surface 60A of the optical element 60 and apart of the lower surface of the barrel PK, and a side surface 7B of apart of the barrel PK which is adjacent to the lower surface 7A. In thisembodiment, the liquid 50 is water. Therefore, the surface treatment,which is in conformity with the affinity for water, is applied to thetip section 7.

The surface treatment, which is applied to the tip section 7 of theprojection optical system PL, is performed in mutually different mannersfor a first surface area AR1 which includes the surface (lower surface)60A of the optical element 60 and the part of the lower surface of thebarrel PK, and for a second surface area AR2 which is disposed aroundthe first surface area AR1 and which includes the remaining area of thelower surface of the barrel PK and the side surface of the barrel PK.Specifically, the surface treatment is applied to the first and secondsurface areas AR1, AR2 respectively so that the affinity of the firstsurface area AR1 for the liquid (water) 50 is higher than the affinityof the second surface area AR2 for the liquid (water) 50. In thisembodiment, a lyophilic or liquid-attracting treatment (hydrophilic orwater-attracting treatment) to give the lyophilicity orliquid-attracting property is applied to the first surface area AR1including the optical element 60, and a lyophobic or liquid-repellingtreatment (hydrophobic or water-repelling treatment) to give thelyophobicity or liquid-repelling property is applied to the secondsurface area AR2. The lyophilic or liquid-attracting treatment refers toa treatment to increase the affinity for the liquid. The lyophobic orliquid-repelling treatment refers to a treatment to decrease theaffinity for the liquid.

The surface treatment is performed depending on the polarity of theliquid 50. In this embodiment, the liquid 50 is water having largepolarity. Therefore, the hydrophilic treatment, which is to be appliedto the first surface area AR1 including the optical element 60, isperformed by forming a thin film with a substance such as alcohol havinga molecular structure of large polarity. Accordingly, the hydrophilicityis given to the first surface area AR1. Alternatively, for example, anO₂ plasma treatment, in which the plasma treatment is performed by usingoxygen (O₂) as a treatment gas, is applied to the barrel PK and thelower surface 60A of the optical element 60 in the first surface areaAR1. Accordingly, oxygen molecules (or oxygen atoms), which have strongpolarity, are gathered on the surface, and thus it is possible to givethe hydrophilicity. As described above, when water is used as the liquid50, it is desirable to perform the treatment for arranging, on thesurface, those having the molecular structure with the large polaritysuch as the OH group in the first surface area AR1. The first surfacearea AR1 includes the optical element 60 as a glass member and thebarrel PK as a metal member. Therefore, when the hydrophilic treatmentis performed, it is possible to perform different surface treatments,for example, such that thin films are formed with different substancesfor the glass member and the metal member respectively. Of course, thesame surface treatment may be applied to the glass member and the metalmember in the first surface area AR1 respectively. When the thin film isformed, it is possible to use techniques including, for example, theapplication and the vapor deposition.

On the other hand, the water-repelling treatment is applied to thesecond surface area AR2 including the surface of the barrel PK. Thewater-repelling treatment, which is to be applied to the second surfacearea AR2, is performed by forming a thin film with a substance having amolecular structure of small polarity including, for example, fluorine.Accordingly, the water-repelling property is given to the second surfacearea AR2. Alternatively, the water-repelling property can be given byapplying a CF₄ plasma treatment in which the plasma treatment isperformed by using carbon tetrafluoride (CF₄) as a treatment gas. It isalso possible to use techniques including, for example, the applicationand the vapor deposition when the thin film is formed in the secondsurface area AR2.

In this embodiment, the surface treatment is also applied to the surfaceof the substrate P in conformity with the affinity for the liquid 50. Inthis case, the hydrophilic or water-attracting treatment is applied tothe surface of the substrate P. As for the hydrophilic treatment for thesubstrate P, the lyophilicity is given to the surface of the substrateP, for example, by forming a thin film with a substance such as alcoholhaving a molecular structure of large polarity as described above. Whenthe surface of the substrate P is surface-treated by applying alcohol orthe like, it is desirable to provide a washing step of washing theapplied film in the step after the exposure and before the subsequentapplication of the photosensitive material, for example, beforetransporting the substrate to a developer/coater.

When the affinity of the first surface area AR1 for the liquid 50 ishigher than the affinity of the second surface area AR2 for the liquid50, the liquid 50 is stably retained in the first surface area AR1.

In this embodiment, the thin film, which is to be used for the surfacetreatment, is formed of a material which is insoluble in the liquid 50.The thin film, which is formed on the optical element 60, is to bearranged on the optical path for the exposure light beam EL. Therefore,the thin film is formed of a material through which the exposure lightbeam EL is transmissive. The film thickness is set to such an extentthat the exposure light beam EL is transmissive therethrough as well.

Next, an explanation will be made about the operation for exposing thesubstrate P with the pattern of the mask M by using the exposureapparatus EX described above.

When the mask M is loaded on the mask stage MST, and the substrate P isloaded on the substrate stage PST, then the control unit CONT drives theliquid supply unit 1 to start the liquid supply operation to the space56. The liquid supply unit 1 supplies the liquid 50 to the space 56along with the direction of movement of the substrate P. For example,when the scanning exposure is performed by moving the substrate P in thescanning direction (−X direction) indicated by the arrow Xa (see FIG.2), the liquid 50 is supplied and recovered with the liquid supply unit1 and the liquid recovery unit 2 by using the supply tube 3, the supplynozzles 4A to 4C, the recovery tube 4, and the recovery nozzles 5(a),5(b). That is, when the substrate P is moved in the −X direction, thenthe liquid 50 is supplied to the space between the projection opticalsystem PL and the substrate P from the liquid supply unit 1 through thesupply tube 3 and the supply nozzles 4 (4A to 4C), and the liquid 50 isrecovered to the liquid recovery unit 2 through the recovery nozzles 5(5(a), 5(b)) and the recovery tube 6. The liquid 50 flows in the −Xdirection so that the space between the lens 60 and the substrate P isfilled therewith. On the other hand, when the scanning exposure isperformed by moving the substrate P in the scanning direction (+Xdirection) indicated by an arrow Xb, then the liquid 50 is supplied andrecovered with the liquid supply unit 1 and the liquid recovery unit 2by using the supply tube 10, the supply nozzles 8(a) to 8C, the recoverytube 11, and the recovery nozzles 9A, 9B. That is, when the substrate Pis moved in the +X direction, then the liquid 50 is supplied from theliquid supply unit 1 to the space between the projection optical systemPL and the substrate P through the supply tube 10 and the supply nozzles8 (8(a) to 8C), and the liquid 50 is recovered to the liquid recoveryunit 2 through the recovery nozzles 9 (9A, 9B) and the recovery tube 11.The liquid 50 flows in the +X direction so that the space between thelens 60 and the substrate P is filled therewith. As described above, thecontrol unit CONT makes the liquid 50 to flow in accordance with themovement direction of the substrate P by using the liquid supply unit 1and the liquid recovery unit 2. In this arrangement, for example, theliquid 50, which is supplied from the liquid supply unit 1 through thesupply nozzles 4, flows so that the liquid 50 is attracted andintroduced into the space 56 in accordance with the movement of thesubstrate P in the −X direction. Therefore, even when the supply energyof the liquid supply unit 1 is small, the liquid 50 can be supplied tothe space 56 with ease. When the direction, in which the liquid 50 ismade to flow, is switched depending on the scanning direction, then itis possible to fill the space between the substrate P and the tipsurface 7 of the lens 60 with the liquid 50, and it is possible toobtain the high resolution and the wide depth of focus, even when thesubstrate P is scanned in any one of the +X direction and the −Xdirection.

In view of the above, it is now assumed that the surface treatment isnot applied to the projection optical system PL and the substrate P.FIG. 5 schematically shows the flow of the liquid 50 in a state in whichthe surface treatment is not applied. In this case, it is assumed thatthe surface of the projection optical system PL and the surface of thesubstrate P have low affinities for the liquid 50.

FIG. 5A shows a state in which the substrate stage PST is stopped. Theliquid 50 is supplied from the supply nozzles 4, and the liquid 50 isrecovered by the recovery nozzles 5. In this situation, the affinity islow between the liquid 50 and the substrate P, and hence the contactangle θ is large. FIG. 5B shows a state in which the substrate P startsthe movement in the X axis direction by the aid of the substrate stagePST. The liquid 50 is deformed as if the liquid 50 is pulled by themoving substrate P. The liquid 50 tends to be separated from the surfaceof the substrate P, because the affinity is low between the liquid 50and the substrate P. FIG. 5C shows a state in which the movementvelocity of the substrate P on the substrate stage PST is furtherincreased. An exfoliation area (bubble) H1 is formed between thesubstrate P and the liquid 50, and an exfoliation area H2 is also formedbetween the optical element 60 and the liquid 50. When the exfoliationareas H1, H2 are formed on the optical path for the exposure light beamEL, the pattern of the mask M is not transferred correctly to thesubstrate P.

FIG. 6 schematically shows the flow of the liquid 50 in a state in whichthe tip section 7 of the projection optical system PL and the surface ofthe substrate P are surface-treated as explained with reference to FIG.4.

FIG. 6A shows a situation in which the substrate stage PST is stopped.The contact angle θ is small, because the affinity is enhanced betweenthe liquid 50 and the substrate P by applying the surface treatment.FIG. 6B shows a state in which the substrate P starts the movement inthe X axis direction by the aid of the substrate stage PST. Even whenthe substrate P is moved, the liquid 50 is not pulled excessively by thesubstrate P, because the affinity is high between the liquid 50 and thesubstrate P. Further, the liquid 50 is not exfoliated from the firstsurface area AR1, because the affinity of the first surface area AR1 ofthe projection optical system PL is also high with respect to the liquid50. In this situation, the circumference of the first surface area AR1is surrounded by the second surface area AR2 which has the low affinityfor the liquid 50. Therefore, the liquid 50 in the space 56 does notoutflow to the outside, and the liquid 50 is stably arranged in thespace 56. FIG. 6C shows a state in which the movement velocity of thesubstrate P on the substrate stage PST is further increased. Even whenthe movement velocity of the substrate P is increased, no exfoliationoccurs between the liquid 50 and the projection optical system PL andthe substrate P, because the surface treatment is applied to theprojection optical system PL and the substrate P.

As explained above, the surface treatment, which is in conformity withthe affinity for the liquid 50, is applied to the surface of thesubstrate P and the tip section 7 of the projection optical system PL asthe portions to make contact with the liquid 50 during the exposureprocess based on the liquid immersion method. Accordingly, it ispossible to suppress the occurrence of inconveniences including, forexample, the exfoliation of the liquid 50 and the generation of thebubble, and it is possible to stably arrange the liquid 50 between theprojection optical system PL and the substrate P. Therefore, it ispossible to maintain a satisfactory pattern transfer accuracy.

The surface treatment, which depends on the affinity for the liquid 50,may be applied to only any one of the tip section 7 of the projectionoptical system PL and the surface of the substrate P.

The foregoing embodiment has been explained such that the surface 60A ofthe optical element 60 and the part of the lower surface of the barrel(holding member) PK are designated as the first surface area AR1, andthe surface treatment is applied to the first surface area AR1 so thatthe affinity for the liquid 50 is enhanced. That is, the explanation hasbeen made assuming that the boundary between the lyophilic orliquid-attracting treatment area and the lyophobic or liquid-repellingtreatment area exists on the lower surface of the barrel PK. However,the boundary may be set on the surface of the optical element 60. Thatis, it is also allowable that the liquid-attracting treatment is appliedto a part of the area of the optical element 60 (at least an areathrough which the exposure light beam passes), and the liquid-repellingtreatment is applied to the remaining area. Of course, it is alsoallowable that the boundary between the liquid-attracting treatment areaand the liquid-repelling treatment area may be coincident with theboundary between the optical element 60 and the barrel PK. That is, itis also allowable that the liquid-attracting treatment is applied toonly the optical element 60. Further, there is no limitation to thesetting of the boundary on the lower surface 7A of the projectionoptical system PL. All of the lower surface 7A of the projection opticalsystem PL may be subjected to the liquid-attracting treatment.

Further, when the surface treatment is performed, it is also possible toallow the lyophilicity (lyophobicity) to have a distribution. In otherwords, the surface treatment can be performed such that the contactangle of the liquid has mutually different values for a plurality ofareas on the surface subjected to the surface treatment. Alternatively,lyophilic areas and lyophobic areas may be appropriately arranged in adivided manner.

The thin film, which is to be used for the surface treatment, may be asingle layer film or a film composed of a plurality of layers. As forthe material for forming the film, it is possible to use arbitrarymaterials provided that the material exhibits desired performance,including, for example, metals, metal compounds, and organic matters.

For example, the thin film formation and the plasma treatment areeffective for the surface treatment for the optical element 60 and thesubstrate P. However, in relation to the surface treatment for thebarrel PK as the metal member, it is possible to adjust the affinity forthe liquid by any physical technique including, for example, the roughsurface treatment for the surface of the barrel PK.

In the embodiment described above, the surface of the substrate P ismade lyophilic (subjected to the liquid-attracting treatment) whilegiving much weight to the stable retention of the liquid between theprojection optical system PL and the substrate P. However, when muchweight is given to the recovery and the removal of the liquid from thesurface of the substrate P, the surface of the substrate P may be madelyophobic (subjected to the liquid-repelling treatment).

In the embodiment described above, the surface treatment, which is inconformity with the affinity for the liquid 50, is applied to the tipsection 7 of the projection optical system PL and the surface of thesubstrate P. However, it is also allowable that any liquid, which is inconformity with the affinity for at least one of the tip section 7 ofthe projection optical system PL and the surface of the substrate P, issupplied from the liquid supply unit 1.

As described above, pure water is used as the liquid 50 in thisembodiment. Pure water is advantageous in that pure water is availablein a large amount with ease, for example, in the semiconductorproduction factory, and pure water exerts no harmful influence, forexample, on the optical element (lens) and the photoresist on thesubstrate P. Further, pure water exerts no harmful influence on theenvironment, and the content of impurity is extremely low. Therefore, itis also expected to obtain the function to wash the surface of thesubstrate P and the surface of the optical element provided at the tipsurface of the projection optical system PL.

It is approved that the refractive index n of pure water (water) withrespect to the exposure light beam EL having a wavelength of about 193nm is approximately in an extent of 1.44 to 1.47. When the ArF excimerlaser beam (wavelength: 193 nm) is used as the light source of theexposure light beam EL, then the wavelength is shortened on thesubstrate P by 1/n, i.e., to about 131 to 134 nm, and a high resolutionis obtained. Further, the depth of focus is magnified about n times,i.e., about 1.44 to 1.47 times as compared with the value obtained inthe air. Therefore, when it is enough to secure an approximatelyequivalent depth of focus as compared with the case of the use in theair, it is possible to further increase the numerical aperture of theprojection optical system PL. Also in this viewpoint, the resolution isimproved.

In this embodiment, the plane parallel plate is attached as the opticalelement 60 to the tip of the projection optical system PL. However, theoptical element, which is attached to the tip of the projection opticalsystem PL, may be an optical plate which is usable to adjust the opticalcharacteristics of the projection optical system PL, for example, theaberration (for example, spherical aberration and comatic aberration),or the optical element may be a lens. On the other hand, when theoptical element, which makes contact with the liquid 50, is the planeparallel plate which is cheaper than the lens, it is enough that theplane parallel plate is merely exchanged immediately before supplyingthe liquid 50 even when any substance (for example, any silicon-basedorganic matter), which deteriorates the transmittance of the projectionoptical system PL, the illuminance of the exposure light beam EL on thesubstrate P, and the uniformity of the illuminance distribution, isadhered to the plane parallel plate, for example, during the transport,the assembling, and/or the adjustment of the exposure apparatus EX. Anadvantage is obtained such that the exchange cost is lowered as comparedwith the case in which the optical element to make contact with theliquid 50 is the lens. That is, the surface of the optical element tomake contact with the liquid 50 is dirtied, for example, due to theadhesion of scattered particles generated from the resist by beingirradiated with the exposure light beam EL or any impurity contained inthe liquid 50. Therefore, it is necessary to periodically exchange theoptical element. However, when the optical element is the cheap planeparallel plate, then the cost of the exchange part is low as comparedwith the lens, and it is possible to shorten the time required for theexchange. Thus, it is possible to suppress the increase in themaintenance cost (running cost) and the decrease in the throughput.

When the pressure, which is generated by the flow of the liquid 50, islarge between the substrate P and the optical element disposed at thetip of the projection optical system PL, it is also allowable that theoptical element is tightly fixed so that the optical element is notmoved by the pressure, rather than allowing the optical element to beexchangeable.

The liquid 50 is water in the embodiment described above. However, theliquid 50 may be any liquid other than water. For example, when thelight source of the exposure light beam EL is the F₂ laser, the F₂ laserbeam is not transmitted through water. Therefore, in this case, thosepreferably usable as the liquid 50 may include, for example,fluorine-based oil (fluorine-based liquid) and perfluoropolyether (PFPE)through which the F₂ laser beam is transmissive. In this case, thesurface of the substrate P and the portion of the projection opticalsystem PL to make contact with the liquid 50 are subjected to theliquid-attracting treatment by forming the thin film, for example, witha substance having a molecular structure of small polarity includingfluorine. Alternatively, other than the above, it is also possible touse, as the liquid 50, those (for example, cedar oil) which have thetransmittance with respect to the exposure light beam EL, which have therefractive index as high as possible, and which are stable against thephotoresist applied to the surface of the substrate P and the projectionoptical system PL. Also in this case, the surface treatment is performeddepending on the polarity of the liquid 50 to be used.

Next, an explanation will be made with reference to FIG. 7 about asecond embodiment of the present invention.

An exposure apparatus EX of this embodiment is designed such that thefollowing conditional expression is satisfied provided that d representsa thickness of the liquid 50 between the lower surface 7A of theprojection optical system PL and the surface of the substrate P (in thiscase, the spacing distance between the projection optical system PL andthe substrate P), v represents a velocity of a flow of the liquid 50between the projection optical system PL and the substrate P, ρrepresents a density of the liquid 50, and μ represents a coefficient ofviscosity of the liquid 50:

(v•d•ρ)/μ≦2,000  (3)

Accordingly, the liquid 50 flows as a laminar flow in the space 56. Asfor the liquid 50, it is also assumed that a plurality of different flowvelocities v exist depending on the position in the liquid. However, itis enough that the maximum velocity V_(max) thereof satisfies theexpression (3).

The control unit CONT adjusts at least one of the amount of supply ofthe liquid per unit time to the space 56 by the aid of the liquid supplyunit 1 and the amount of recovery of the liquid per unit time from thespace 56 by the aid of the liquid recovery unit 2 so that theconditional expression (3) is satisfied. Accordingly, the velocity v ofthe liquid 50 to flow through the space 56 is determined, and it ispossible to satisfy the conditional expression (3). When the conditionalexpression (3) is satisfied, the liquid 50 flows through the space 56while forming the laminar flow.

Alternatively, the control unit CONT can also satisfy the conditionalexpression (3) by adjusting the movement velocity in the scanningdirection of the substrate P by the substrate stage PST. That is, thevelocity v of the liquid 50 flowing through the space 56 is alsodetermined by the movement velocity of the substrate P in some cases.That is, there is such a possibility that the liquid 50 on the substrateP may flow such that the liquid 50 is pulled by the substrate P inaccordance with the movement of the substrate P. In this case, theconditional expression (3) can be satisfied by adjusting the movementvelocity of the substrate P. For example, when the substrate P and theliquid 50 flow or move at approximately identical velocities withrespect to the projection optical system PL, it is appropriate that themovement velocity of the substrate P may be regarded as the velocity vof the liquid 50 to satisfy the conditional expression (3). Also in thiscase, the liquid 50 flows through the space 56 while forming the laminarflow. Further, in this case, it is not necessarily indispensable tooperate the liquid supply unit 1 and the liquid recovery unit 2 duringthe exposure for the substrate P. The flow of the liquid 50 can be madeto be the laminar flow by adjusting only the movement velocity of thesubstrate P.

In order to satisfy the conditional expression (3), the thickness d ofthe liquid 50 (i.e., the spacing distance between the projection opticalsystem PL and the substrate P) may be previously set as a designed valuefor the exposure apparatus, and the velocity v may be determined on thebasis of this value. Alternatively, the velocity v may be previously setas a designed value, and the thickness (distance) d may be determined onthe basis of this value.

In order that the liquid 50 flows while forming the laminar flow in thespace 56, for example, slits may be provided at openings of the supplynozzles 4 connected to the liquid supply unit 1 as shown in FIG. 8A, orporous members are provided at openings of the supply nozzles 4 as shownin FIG. 8B. Accordingly, the liquid 50 can be rectified to flow in thelaminar flow state.

When the liquid 50 flows as the laminar flow, it is possible to suppressinconveniences such as the vibration and the change in the refractiveindex which would be otherwise caused by the fluctuation of thepressure. Thus, it is possible to maintain a satisfactory patterntransfer accuracy. Further, when the surface treatment is applied to thesurface of the substrate P and the portion of the projection opticalsystem PL to make contact with the liquid 50, and the exposure apparatusEX is set so that the conditional expression (3) is satisfied to performthe exposure process, then the liquid 50 in the space 56 is establishedto be in a more satisfactory state in which no influence is exerted onthe pattern transfer accuracy.

In the embodiment described above, the exposure apparatus is adopted, inwhich the space between the projection optical system PL and thesubstrate P is locally filled with the liquid. However, the presentinvention is also applicable to a liquid immersion exposure apparatus inwhich a stage holding a substrate as an exposure objective is moved in aliquid bath, and a liquid immersion exposure apparatus in which a liquidpool having a predetermined depth is formed on a stage and a substrateis held therein. The structure and the exposure operation of the liquidimmersion exposure apparatus in which the stage holding the substrate asthe exposure objective is moved in the liquid bath are disclosed, forexample, in Japanese Patent Application Laid-open No. 6-124873, contentof which is incorporated herein by reference within a range ofpermission of the domestic laws and ordinances of the state designatedor selected in this international application. The structure and theexposure operation of the liquid immersion exposure apparatus in whichthe liquid pool having the predetermined depth is formed on the stageand the substrate is held therein are disclosed, for example, inJapanese Patent Application Laid-open No. 10-303114 and U.S. Pat. No.5,825,043, contents of which are incorporated herein by reference withina range of permission of the domestic laws and ordinances of the statedesignated or selected in this international application.

In the embodiment described above, the liquid supply unit 1 and theliquid recovery unit 2 are used to continue the supply and the recoveryof the liquid 50 during the exposure for the substrate P as well.However, it is also allowable to stop the supply and the recovery of theliquid 50 by the liquid supply unit 1 and the liquid recovery unit 2during the exposure for the substrate P. That is, a small amount of theliquid 50 is supplied by the liquid supply unit 1 onto the substrate Pto such an extent that the liquid immersion portion, which has athickness of not more than the working distance of the projectionoptical system PL (about 0.5 to 1.0 mm), is formed between the substrateP and the tip section 7 of the projection optical system PL, or to suchan extent that a thin liquid film is formed on the entire surface of thesubstrate P before the start of the exposure for the substrate P. Thetip section 7 of the projection optical system PL and the substrate Pare made to tightly contact with each other by the aid of the liquid 50.The spacing distance between the tip section 7 of the projection opticalsystem PL and the substrate P is not more than several mm. Therefore,even when the substrate P is moved without supplying and recovering theliquid by using the liquid supply unit 1 and the liquid recovery unit 2during the exposure for the substrate P, it is possible to continuouslyretain the liquid 50 between the projection optical system PL and thesubstrate P owing to the surface tension of the liquid 50. The resist(photosensitive film), which is disposed on the substrate P, is notdamaged by the supply of the liquid from the liquid supply unit 1 aswell. In this case, when a coating for repelling the liquid 50(water-repelling coating when the liquid is water) is applied with apredetermined width to the circumferential edge of the substrate P, itis possible to avoid the outflow of the liquid 50 from the substrate P.It goes without saying that the conditional expression (3) is satisfiedto generate no turbulence in the liquid 50 when the substrate P ismoved.

In the embodiment described above, the liquid (50) is supplied on thesubstrate stage PST. However, the liquid may be supplied onto thesubstrate P before the substrate P is imported onto the substrate stagePST. In this case, when the liquid, which is supplied to a part or allof the surface of the substrate P, has a thickness of about 0.5 to 1.0mm, then the substrate P can be imported to the substrate stage PST andthe substrate P can be exported from the substrate stage PST whileplacing the liquid on the substrate P by the surface tension. Also inthis case, when a liquid-repelling coating having a predetermined widthis applied to the circumferential edge of the substrate P, it ispossible to enhance the retaining force for the liquid on the substrateP. When the substrate P is imported to the substrate stage PST and thesubstrate P is exported from the substrate stage PST while retaining theliquid on the substrate P as described above, it is possible to omit themechanism for supplying and recovering the liquid on the substrate stagePST.

The embodiment described above is constructed such that the spacebetween the projection optical system PL and the surface of thesubstrate P is filled with the liquid 50. However, for example, as shownin FIG. 9, the space may be filled with the liquid 50 in a state inwhich a cover glass 65, which is composed of a plane parallel plate, isattached to the surface of the substrate P. In this arrangement, thecover glass 65 is supported over the Z stage 51 by the aid of a supportmember 66. The space 57, which is formed by the cover glass 65, thesupport member 66, and the Z stage 51, is a substantially tightly closedor sealed space. The liquid 50 and the substrate P are arranged in thespace 57. The cover glass 65 is composed of a material through which theexposure light beam EL is transmissive. The liquid 50 is supplied to andrecovered from a space 56′ between the surface of the cover glass 65 andthe projection optical system PL by using the liquid supply unit 1 andthe liquid recovery unit 2. The setting is made such that theconditional expression (3) described above is satisfied in the space 56′provided that d represents the spacing distance between the surface ofthe cover glass 65 and the tip section 7 of the projection opticalsystem PL.

The surface treatment, which is in conformity with the affinity for theliquid 50, can be also applied to the surface (upper surface) of thecover glass 65. It is desirable that the liquid-attracting treatment isapplied to the surface of the cover glass 65. Therefore, when the liquid50 is water, a thin film is formed with a substance having a molecularstructure of large polarity on the surface of the cover glass 65.

The substrate P, which is usable in the respective embodiments describedabove, is not limited to the semiconductor wafer for producing thesemiconductor device. Those applicable include, for example, the glasssubstrate for the display device, the ceramic wafer for the thin filmmagnetic head, and the master plate (synthetic quartz, silicon wafer)for the mask or the reticle to be used for the exposure apparatus.

As for the exposure apparatus EX, the present invention is alsoapplicable to the scanning type exposure apparatus (scanning stepper)based on the step-and-scan system for performing the scanning exposurefor the pattern of the mask M by synchronously moving the mask M and thesubstrate P as well as the projection exposure apparatus (stepper) basedon the step-and-repeat system for performing the full field exposure forthe pattern of the mask M in a state in which the mask M and thesubstrate P are made to stand still, while successively step-moving thesubstrate P. The present invention is also applicable to the exposureapparatus based on the step-and-stitch system in which at least twopatterns are partially overlaid and transferred on the substrate P.

The present invention is also applicable to a twin-stage type exposureapparatus. The structure and the exposure operation of the twin-stagetype exposure apparatus are disclosed, for example, in Japanese PatentApplication Laid-open Nos. 10-163099 and 10-214783 (corresponding toU.S. Pat. Nos. 6,341,007, 6,400,441, 6,549,269, and 6,590,634),Published Japanese Translation of PCT International Publication forPatent Application No. 2000-505958 (corresponding to U.S. Pat. No.5,969,441), and U.S. Pat. No. 6,208,407, contents of which areincorporated herein by reference within a range of permission of thedomestic laws and ordinances of the state designated or selected in thisinternational application.

As for the type of the exposure apparatus EX, the present invention isnot limited to the exposure apparatus for the semiconductor productionapparatus for exposing the substrate P with the semiconductor devicepattern. The present invention is also widely applicable, for example,to the exposure apparatus for producing the liquid crystal displaydevice or for producing the display as well as the exposure apparatusfor producing, for example, the thin film magnetic head, the imagepickup device (CCD), the reticle, or the mask.

When the linear motor is used for the substrate stage PST and/or themask stage MST, it is allowable to use any one of those of the airfloating type based on the use of the air bearing and those of themagnetic floating type based on the use of the Lorentz's force or thereactance force. Each of the stages PST, MST may be either of the typein which the movement is effected along the guide or of the guidelesstype in which no guide is provided. An example of the use of the linearmotor for the stage is disclosed in U.S. Pat. Nos. 5,623,853 and5,528,118, contents of which are incorporated herein by referencerespectively within a range of permission of the domestic laws andordinances of the state designated or selected in this internationalapplication.

As for the driving mechanism for each of the stages PST, MST, it is alsoallowable to use a plane motor in which a magnet unit provided withtwo-dimensionally arranged magnets and an armature unit provided withtwo-dimensionally arranged coils are opposed to one another, and each ofthe stages PST, MST is driven by the electromagnetic force. In thisarrangement, any one of the magnet unit and the armature unit isconnected to the stage PST, MST, and the other of the magnet unit andthe armature unit is provided on the side of the movable surface of thestage PST, MST.

The reaction force, which is generated in accordance with the movementof the substrate stage PST, may be mechanically released to the floor(ground) by using a frame member so that the reaction force is nottransmitted to the projection optical system PL. The method for handlingthe reaction force is disclosed in detail, for example, in U.S. Pat. No.5,528,118 (Japanese Patent Application Laid-open No. 8-166475), contentsof which are incorporated herein by reference within a range ofpermission of the domestic laws and ordinances of the state designatedor selected in this international application.

The reaction force, which is generated in accordance with the movementof the mask stage MST, may be mechanically released to the floor(ground) by using a frame member so that the reaction force is nottransmitted to the projection optical system PL. The method for handlingthe reaction force is disclosed in detail, for example, in U.S. Pat. No.5,874,820 (Japanese Patent Application Laid-open No. 8-330224), contentsof which are incorporated herein by reference within a range ofpermission of the domestic laws and ordinances of the state designatedor selected in this international application.

As described above, the exposure apparatus EX according to theembodiment of the present invention is produced by assembling thevarious subsystems including the respective constitutive elements asdefined in claims so that the predetermined mechanical accuracy, theelectric accuracy, and the optical accuracy are maintained. In order tosecure the various accuracies, those performed before and after theassembling include the adjustment for achieving the optical accuracy forthe various optical systems, the adjustment for achieving the mechanicalaccuracy for the various mechanical systems, and the adjustment forachieving the electric accuracy for the various electric systems. Thesteps of assembling the various subsystems into the exposure apparatusinclude, for example, the mechanical connection, the wiring connectionof the electric circuits, and the piping connection of the air pressurecircuits in correlation with the various subsystems. It goes withoutsaying that the steps of assembling the respective individual subsystemsare performed before performing the steps of assembling the varioussubsystems into the exposure apparatus. When the steps of assembling thevarious subsystems into the exposure apparatus are completed, theoverall adjustment is performed to secure the various accuracies as theentire exposure apparatus. It is desirable that the exposure apparatusis produced in a clean room in which, for example, the temperature andthe cleanness are managed.

As shown in FIG. 10, the microdevice such as the semiconductor device isproduced by performing, for example, a step 201 of designing thefunction and the performance of the microdevice, a step 202 ofmanufacturing a mask (reticle) based on the designing step, a step 203of producing a substrate as a base material for the device, an exposureprocess step 204 of exposing the substrate with a pattern of the mask byusing the exposure apparatus EX of the embodiment described above, astep 205 of assembling the device (including a dicing step, a bondingstep, and a packaging step), and an inspection step 206. The exposureprocess step 204 includes a step of performing the surface treatment forthe substrate in order to adjust the hydrophilicity for the substrateand the liquid before the exposure.

According to the present invention, it is possible to suppress theexfoliation of the liquid, the generation of the bubble, or theoccurrence of the turbulence, and it is possible to maintain the liquidin a desired state between the projection optical system and thesubstrate in the liquid immersion exposure. Accordingly, the pattern canbe transferred correctly with a wide depth of focus. Therefore, thepresent invention is extremely useful for the exposure based on the useof the short wavelength light source such as ArF. It is possible toproduce a highly integrated device having desired performance.

1. A liquid immersion exposure apparatus comprising: an optical memberthrough which an exposure beam passes; a flow passage in which a liquidflows, the flow passage being in fluidic communication with a spacebetween the optical member and an object opposite to the optical member;and an opening at which a plurality of slits are provided, and fromwhich the liquid is supplied to the space through the flow passage. 2.The apparatus according to claim 1, wherein the liquid flows as alaminar flow in the space.
 3. The apparatus according to claim 1,wherein the object is a substrate having a resist coating to which theexposure beam is irradiated through the optical member and the liquid inthe space.
 4. The apparatus according to claim 1, wherein the object isa substrate having a coating which is liquid repellent against theliquid.
 5. The apparatus according to claim 4, wherein the liquid issupplied so as to form a liquid immersion area on a portion of thesubstrate during the exposure.
 6. The apparatus according to claim 4,wherein the liquid flows as a laminar flow in the space.
 7. A devicemanufacturing method comprising: exposing a substrate by use of anexposure apparatus as recited in claim 1; and processing the exposedsubstrate.
 8. A device manufacturing method comprising: supplying aliquid from an opening at which a plurality of slits are provided;filling a space between a substrate and an optical member with theliquid supplied from the opening; and exposing the substrate with apatterned beam through the liquid in the space and the optical member.9. The method according to claim 8, wherein the liquid flows as alaminar flow in the space.
 10. The method according to claim 8, whereinthe substrate has a coating which is liquid repellent against theliquid.
 11. The method according to claim 10, wherein the liquid issupplied so as to form a liquid immersion area on a portion of thesubstrate during the exposure.
 12. The method according to claim 10,wherein the liquid flows as a laminar flow in the space.